Method for manufacturing CMOS image sensor having microlens therein with high photosensitivity

ABSTRACT

The method for manufacturing a CMOS image sensor is employed to prevent bridge phenomenon between adjacent microlenses by employing openings between the microlenses. The method includes the steps of: preparing a semiconductor substrate including isolation regions and photodiodes therein obtained by a predetermined process; forming an interlayer dielectric (ILD), metal interconnections and a passivation layer formed on the semiconductor substrate in sequence; forming a color filter array having a plurality of color filters on the passivation layer; forming an over-coating layer (OCL) on the color filter array by using a positive photoresist or a negative photoresist; forming openings in the OCL by patterning the OCL by using a predetermined mask; and forming dome-typed microlenses on a patterned OCL.

The present patent application is a Divisional of application Ser. No.10/737,227, filed Dec. 16, 2003 now U.S. Pat. No. 6,979,588.

FIELD OF THE INVENTION

The present invention relates to a method for manufacturing asemiconductor device; and, more particularly, to a method formanufacturing a complementary metal oxide semiconductor (CMOS) imagesensor having microlenses therein with a high photosensitivity byforming openings between the microlenses.

DESCRIPTION OF THE PRIOR ART

As is well known, an image sensor is a semiconductor device convertingan optical image to an electrical signal. Among various types of theimage sensors, a charged coupled device (CCD) image sensor uses aplurality of metal-oxide-silicon (MOS) capacitors therein so that chargecarriers are stored and transferred by the MOS capacitors. Meanwhile, acomplementary MOS (CMOS) image sensor is a semiconductor device thatconverts an optical image to an electrical signal using a CMOSmanufacturing technology, which employs a switching scheme of an MOStransistor for transportation of photo-electric charges from aphotodiode to an output node as well as detection of an output signal atthe output node.

The CCD image sensor has many demerits that complicated operationmethods, high power consumption and a number of mask processes arerequired. Furthermore, it is very difficult to make a signal processingcircuit integrated into a CCD chip. Accordingly, in order to overcomesuch demerits, many developments for the CMOS image sensor have beenrecently ensued using a submicron CMOS manufacturing technique. The CMOSimage sensor creates a picture by detecting signals from the photodiodeand the MOS transistors in a unit pixel. The use of a CMOS manufacturingtechnique can reduce power consumption compared with a CCD. Furthermore,while it is necessary to perform about 30 to 40 mask processes formanufacturing the CCD image sensor, the method for manufacturing theCMOS image sensor requires only about 20 mask processes, therebysimplifying the manufacturing process. Since an image signal processingcircuit can be integrated together with light-sensing elements in onechip, the CMOS image sensor is highlighted as a next generation imagesensor.

As well known, to embody color images in an image sensor, a color filterarray is arranged over a pixel array, wherein color filter array usuallyincludes an organic material that only transmits light with a specificwavelength band. For example, a blue color filter transmits light withthe blue wavelength band and shields light with other wavelength band.The color filter array includes generally three colors of red, green andblue, or those of yellow, magenta and cyan.

The CMOS image sensor includes a pixel array for sensing the lights andaccumulating photocharges and a logic circuit for processing the signalfrom the pixel array. In order to improve the photosensitivity of theCMOS image sensor, there have been proceeded endeavors to increase thearea ratio of the photosensitive parts in the unit pixel, i.e., a fillfactor. However, there are fundamentally limits in such endeavors,because the logic circuit parts can not be completely eliminated andthus, the photosensitive part has a limited area. Accordingly, in orderto increase the photosensitivity, light-collecting technique has beenresearched. Using this technique, the pathways of the incident lightsprojected on the regions other than the photosensitive parts arechanged, whereby much light is collected in the photosensitive parts.For collecting much more lights effectively, the image sensor employsmicrolenses on the color filter array.

There is provided in FIG. 1 a cross sectional view setting forth aconventional method for manufacturing the CMOS image sensor havingmicrolenses therein.

In FIG. 1, the conventional method for manufacturing the CMOS imagesensor begins with preparing a semiconductor substrate 110 obtained by apredetermined process. Isolation regions 112 are formed in thesemiconductor substrate 110, thereby defining an active region and afield region. In each unit pixel, there is formed a correspondingphotodiode 114 for converting an incident light to photocharges. For thesake of convenience, transistors required for the unit pixel is notdepicted in the drawings.

After forming the isolation regions 112 and the photodiodes 114, aninterlayer dielectric (ILD) 116 is formed on the semiconductor substrate110. Thereafter, metal interconnections 118 are formed on predeterminedlocations of the ILD 116 in consideration of the underlying photodiodes114 so that the incident light projected on the photodiodes 114 is notshielded by the existence of the metal interconnections 118.

Following a formation of the metal interconnections 118, a passivationlayer 129 is formed over the resultant structure including the metalinterconnections 118 for protecting a device from moisture and a scratchduring post manufacturing processes.

Subsequently, color filter array 122 having a red, a green and a bluecolor filters is formed directly on the passivation layer 120 by using atypical method. Alternatively, after a planarized layer (not shown) isformed on the passivation layer 120, the color filter array 122 can beformed on the planarized layer. Each color filter is formed in acorresponding unit pixel for transmitting only a color with apredetermined wavelength band among a plurality of waves in the incidentlight. Herein, the color filter array 122 uses an exemplary dyedphotoresist or a photoresist containing pogment.

While forming the color filter array 122, boundaries between the colorfilters are overlapped each other so as to form micro-stepstherebetween. In order to form microlenses, however, an underlying layeron which microlenses will be formed should be planarized. Thus, an overcoating layer (OCL) 124 is formed on the color filter array 122 forproviding a planarized surface by using the photoresist material.

Afterward, a microlens layer is formed on the OCL 124 by using a methodsuch as a spin on coating. Thereafter, the microlens layer is patternedinto a predetermined configuration by using a predetermined mask,thereby forming a rectangular microlens correspondent to each unitpixel.

Finally, a thermal flow process is carried out to convert therectangular microlenses to dome-typed microlenses 128, as shown in FIG.1.

In the CMOS image sensor, as the dome-typed microlenses 128 are widerand wider, much more lights are concentrated in the photodiodes 114 toenhance a photosensitivity. However, as the dome-typed microlenses 128are wider, it causes a problem that there may be happened a bridgephenomenon (‘A’) between the adjacent microlenses 128 during the thermalflow process. That is, according to the conventional method formanufacturing the CMOS image sensor having the microlenses therein,overflowed substances are collected between adjacent microlenses 128during the flow process so that end portions of the dome-typedmicrolenses 128 cling together. Accordingly, such a bridge phenomenon(‘A’) incurs a poor photosensitivity of the CMOS image sensor. Moreover,since the dome-typed microlenses 128 are not aligned uniformly within anarea of a corresponding unit pixel, it deteriorates an optical propertyin the long run.

SUMMARY OF THE INVENTION

It is, therefore, an object of the present invention to provide a methodfor manufacturing a complementary metal oxide semiconductor (CMOS) imagesensor having microlenses therein with an enhanced photosensitivity andan optical property by introducing openings between the microlenses.

In accordance with a first aspect of the present invention, there isprovided a method for manufacturing a complementary metal oxidesemiconductor (CMOS) image sensor having microlenses therein, the methodincluding the steps of: a) preparing a semiconductor substrate includingisolation regions and photodiodes therein obtained by a predeterminedprocess; b) forming an interlayer dielectric (ILD), metalinterconnections and a passivation layer formed on the semiconductorsubstrate in sequence; c) forming a color filter array having aplurality of color filters on the passivation layer; d) forming anover-coating layer (OCL) on the color filter array by using a positivephotoresist; e) forming openings in the OCL by patterning the OCL byusing a binary mask, wherein the binary mask has coated portions anduncoated portions, the uncoated portions being disposed above boundariesbetween the color filters; and f) forming dome-typed microlenses on apatterned OCL.

In accordance with a second aspect of the present invention, there isprovided a method for manufacturing a complementary metal oxidesemiconductor (CMOS) image sensor having microlenses therein, the methodincluding the steps of: a) preparing a semiconductor substrate includingisolation regions and photodiodes therein obtained by a predeterminedprocess; b) forming an ILD, metal interconnections and a passivationlayer formed on the semiconductor substrate in sequence; c) forming acolor filter array having a plurality of color filters on thepassivation layer; d) forming an OCL on the color filter array by usinga negative photoresist; e) forming openings in the OCL by patterning theOCL by using a binary mask, wherein the binary mask has coated portionsand uncoated portions, the coated portions being disposed aboveboundaries between the color filters; and f) forming dome-typedmicrolenses on a patterned OCL.

In accordance with a third aspect of the present invention, there isprovided a method for manufacturing a complementary metal oxidesemiconductor (CMOS) image sensor having microlenses therein, the methodincluding the steps of: a) preparing a semiconductor substrate includingisolation regions and photodiodes therein obtained by a predeterminedprocess; b) forming an ILD, metal interconnections and a passivationlayer formed on the semiconductor substrate in sequence; c) forming acolor filter array having a plurality of color filters on thepassivation layer; d) forming an OCL on the color filter array by usinga negative photoresist; e) forming openings in the OCL by patterning theOCL by using a phase shifted mask (PSM), wherein the PSM has a 0° phaseand a 180° phase, boundaries between the 0° phase and the 180° phasebeing disposed above boundaries between the color filters; and f)forming dome-typed microlenses on a patterned OCL.

In accordance with a fourth aspect of the present invention, there isprovided a method for manufacturing a complementary metal oxidesemiconductor (CMOS) image sensor having microlenses therein, the methodincluding the steps of: a) preparing a semiconductor substrate includingisolation regions and photodiodes therein obtained by a predeterminedprocess; b) forming an ILD, metal interconnections and a passivationlayer formed on the semiconductor substrate in sequence; c) forming afirst OCL, color filters, a second OCL and a third OCL on thepassivation layer sequentially; d) patterning the third OCL into apreset configuration, thereby forming openings and a patterned thirdOCL; and e) forming dome-typed microlenses by carrying out a flowprocess.

BRIEF DESCRIPTION OF THE DRAWINGS

The above and other objects and features of the present invention willbecome apparent from the following description of the preferredembodiments given in conjunction with the accompanying drawings, inwhich:

FIG. 1 is a cross sectional view setting forth a conventional method formanufacturing a complementary metal oxide semiconductor (CMOS) imagesensor having microlenses therein;

FIGS. 2A to 2D are cross sectional views setting forth a method formanufacturing a CMOS image sensor having microlenses therein inaccordance with a first preferred embodiment of the present invention;

FIGS. 3A to 3D are cross sectional views setting forth a method formanufacturing a CMOS image sensor having microlenses therein inaccordance with a second preferred embodiment of the present invention;

FIGS. 4A to 4D are cross sectional views setting forth a method formanufacturing a CMOS image sensor having microlenses therein inaccordance with a third preferred embodiment of the present invention;

FIGS. 5A to 5E are cross sectional views setting forth a method formanufacturing a CMOS image sensor having microlenses therein inaccordance with a fourth preferred embodiment of the present invention;and

FIG. 6 is a plane view setting forth an arrangement of each element in aunit pixel array of a CMOS image sensor in accordance with the fourthpreferred embodiment of the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

There are provided in FIGS. 2 to 6 cross sectional views and a planeview setting forth a method for manufacturing a complementary metaloxide semiconductor (CMOS) image sensor in accordance with preferredembodiments of the present invention.

Referring to FIGS. 2A to 2D, there are shown cross sectional viewssetting forth a method for manufacturing a CMOS image sensor havingmicrolenses therein in accordance with a first preferred embodiment ofthe present invention.

In FIG. 2A, a first inventive method for manufacturing the CMOS imagesensor begins with preparing a semiconductor substrate 210 obtained by apredetermined process. Isolation regions 212 are formed in thesemiconductor substrate 210, thereby defining an active region and afield region. In each unit pixel, there is formed a correspondingphotodiode 214 for converting an incident light to photocharges. For thesake of convenience, transistors required for the unit pixel are notdepicted in the drawings.

After preparing the semiconductor substrate 210, an interlayerdielectric (ILD) 216 is formed on the semiconductor substrate 210.Thereafter, metal interconnections 218 are formed on predeterminedlocations of the ILD 216 in consideration of underlying photodiodes 214so that the incident light projected on the photodiodes 214 is notshielded by the existence of the metal interconnections 218.

Following the formation of the metal interconnections 218, a passivationlayer 220 is formed over the resultant structure including the metalinterconnections 218 for protecting a device from moisture and a scratchduring post processes.

Subsequently, a color filter array 222 having three kinds of colorfilters is formed for transmitting only colors with predeterminedwavelength bands among a plurality of waves in the incident light.Herein, the color filter array 222 is generally formed by using a dyedphotoresist or a photoresist containing pogment, of which boundaries areoverlapped each other so as to form micro-steps therebetween. In orderto form microlenses 228A, however, an underlying layer on which themicrolenses 228A will be formed should be planarized. Thus, anover-coating layer (OCL) 224 is formed on the color filter array 222 byusing a positive photoresist correspondent to a post binary mask, forproviding a planarized surface.

Thereafter, the mask 226 is prepared by making use of a conventionalbinary mask having uncoated portions 226A and coated portions 226B,wherein the uncoated portions 226A are disposed above boundaries of thecolor filters. The coated portions 226B are situated above the colorfilters which are coated with chromium (Cr). Herein, the uncoatedportions 226A have widths (d1) of less than a maximum resolution andpreferably, the widths of the uncoated portions 226A are less than about0.2 μm in the first preferred embodiment of the present invention. Sincethe mask 226 has the uncoated portions 226A, it is possible to adjustcritical dimensions (CD) of openings 205 and depths of the openings 205by controlling the dose amount.

Afterward, referring to FIG. 2B, since the OCL 224 uses the positivephotoresist, the OCL 224 under the uncoated portions 226A of the mask226 is patterned into a predetermined shape and the OCL 224 under thecoated portions 226B is left intact on the contrary, thereby forming theopenings 205 and a patterned OCL 224A. Meanwhile, it is not necessary toform the wide and the deep openings 205 for preventing a bridgephenomenon during a post flow process. Thus, it is sufficient to formthe small openings 205 having the widths less than the maximumresolution for preventing a bridge phenomenon. That is, in the firstpreferred embodiment, the openings 205 can be formed with the widths inthe range of about 0.1 μm to about 0.2 μm by controlling the doseamount. After formation of the openings 205, a curing process is carriedout for hardening the patterned OCL 224A.

Subsequently, referring to FIG. 2C, a microlens layer is formed on thepatterned OCL 224A and the openings 205 by employing a material such asa silicon oxide-based photoresist with a high optical transmittanceproperty. Then the microlens layer is patterned into a predeterminedconfiguration so as to form rectangular microlenses 228. It is notedthat the rectangular microlens 228 should be formed with a predeterminedwidth in consideration of a post flow process. That is, the width of therectangular microlens 226 should be smaller than the width of thepatterned OCL 224A between the openings 205.

Finally, referring to FIG. 2D, the flow process is carried out, therebyforming dome-typed microlenses 228A. Herein, overflowed substances 215detached from the rectangular microlenses 228 during the flow processare collected in the openings 205, whereby a bridge phenomenon betweenthe adjacent microlenses 228A are effectively prevented. Moreover, sincethere is no bridge phenomenon, it is possible to enlarge the microlensesas wide as possible so that a photosensitivity of the CMOS image sensorcan be enhanced without increasing a manufacturing cost because of usingthe conventional binary mask as the mask 226.

Referring to FIGS. 3A to 3D, there are provided cross sectional viewssetting forth a method for manufacturing a CMOS image sensor havingmicrolenses therein in accordance with a second preferred embodiment ofthe present invention.

In FIG. 3A, a second method for manufacturing the CMOS image sensorbegins with preparing a semiconductor substrate 310 obtained by apredetermined process. Since the processes for forming isolation regions312, photodiodes 314, an ILD 316, metal interconnections 318, apassivation layer 320 and color filter array 322 are same to those ofthe first embodiment, further description will be abbreviated herein.

After carrying out above processes, an OCL 324 of a negative photoresistis formed on the color filter array 322 for providing a planarizedsurface where microlenses will be formed. Thereafter, a mask 326 isprepared by making use of a conventional binary mask having coatedportions 326A and uncoated portions 326B therein, wherein the coatedportions 326A are disposed above boundaries between the color filters322 and the uncoated portions 326B are situated above the color filters.

Subsequently, referring to FIG. 3B, the OCL 324 is patterned into apredetermined configuration by using the mask 326. In detail, since theOCL 324 uses the negative photoresist in the second embodiment, portionsof the OCL 324 under the coated portions 326A of the mask 326 arepatterned and the other portions of the OCL 324 under the uncoatedportions 326B are left intact, thereby forming openings 305 and apatterned OCL 324A. After forming the openings 305, a curing process iscarried out for hardening the patterned OCL 324A.

Following the formation of the openings 305, referring to FIG. 3C, amicrolens layer is formed on the patterned OCL 324A and the openings 305by employing a silicon oxide-based photoresist and is patterned into apredetermined configuration so as to form rectangular microlenses 328.It is noted that the rectangular microlens 328 should be formed with apredetermined width in consideration of a post flow process. That is,the width of the rectangular microlens 328 should be smaller than thewidth of the patterned OCL 324 between the openings 305.

Finally, referring to FIG. 3D, the flow process is carried out, therebyforming dome-typed microlenses 328A. Herein, overflowed substances 315detached from the rectangular microlenses 328 during the flow processare collected in the openings 305, whereby a bridge phenomenon betweenthe adjacent microlenses 328A are effectively prevented like the firstembodiment.

Referring to FIGS. 4A to 4D, there are provided cross sectional viewssetting forth a method for manufacturing a CMOS image sensor havingmicrolenses therein in accordance with a third preferred embodiment ofthe present invention.

In the third preferred embodiment of the present invention, there isused a phase shifting mask (PSM) instead of the conventional binary maskin order to increase resolution. In general, the light passing throughthe PSM has 0° phase or 180° phase so that there is happened adestructive interference between 0° phase and 180° phase, i.e., zerolight intensity, thereby improving resolution and depth of focus (DOF)in optical lithography.

In FIG. 4A, a third method for manufacturing the CMOS image sensorbegins with preparing a semiconductor substrate 410 obtained by apredetermined process. Since the processes for forming isolation regions412, photodiodes 414, an ILD 416, metal interconnections 418, apassivation layer 420 and a color filter array 422 are same to those ofthe first and the second embodiments, further descriptions will beabbreviated herein.

After carrying out above processes, an OCL 424 is formed on the colorfilter array 422 for providing a planarized layer where microlenses willbe formed. Herein, the OCL 424 uses a negative photoresist.

Subsequently, referring to FIG. 4B, the OCL 424 is patterned into apredetermined configuration by using the PSM 426. That is, since lightintensity is about zero at around boundaries of 0° phase and 180° phase,portions of the OCL 424 under the boundaries are patterned and the otherportions of the OCL 424 are left intact so that openings 405 and apatterned OCL 424A are formed. After forming the openings 405, a curingprocess is carried out for hardening the patterned OCL 424. The thirdembodiment employs the PSM 426 so as to form much more delicate openings405 with the width in the range of about 0.03 μm to about 0.1 μm,thereby maximizing the width of the microlens in comparison with thefirst and the second embodiments making use of the binary mask.

Following the formation of the openings 405, referring to FIG. 4C, amicrolens layer is formed on the patterned OCL 424 and the openings 405by employing a material such as a silicon oxide-based photoresist and ispatterned into a predetermined configuration so as to form rectangularmicrolenses 428. It is noted that the rectangular microlens 428 shouldbe formed with a predetermined width in consideration of a post flowprocess. That is, the width of the rectangular microlens 428 should besmaller than the width of the patterned OCL 424A between the openings405.

Finally, referring to FIG. 4D, the flow process is carried out so as toform dome-typed microlenses 428A. Herein, overflowed substances 415detached from the rectangular microlenses 428 produced during the flowprocess are collected in the openings 405, whereby a bridge phenomenonbetween the adjacent microlenses 428A are effectively prevented.

Referring to FIGS. 5A to 5E, there are provided cross sectional viewssetting forth a method for manufacturing a CMOS image sensor havingmicrolenses therein in accordance with a fourth preferred embodiment ofthe present invention.

In FIG. 5A, the fourth method for manufacturing the CMOS image sensorbegins with preparing a semiconductor substrate 510 obtained by apredetermined process. Then, since the processes for forming isolationregions 512, photodiodes 514, an ILD 516, metal interconnections 518 anda passivation layer 520 are same to those of the first, the second andthe third embodiments, further descriptions are abbreviated herein.Furthermore, MOS transistors required in the CMOS image sensor are notdepicted in the drawings for the sake of convenience.

After carrying out the above processes, a first OCL 521 such as aphotoresist material is formed on the passivation layer 520 with thethickness of about 6,500 Å, for providing a planarized surface where acolor filter array 522 will be formed.

Thereafter, the color filter array 522 is formed on a top face of thefirst OCL 521. In the fourth preferred embodiment, since the colorfilter array 522 is formed on the planarized layer, i.e., the first OCL521, it is possible to form the color filter array 522 uniformly incomparison with the first, the second and the third embodiments.

Following the formation of the color filter array 522, a curing processis carried out for about three minutes at about 220° C., in order toprevent an inter-reaction and a chemical attack which may be happenedbetween materials in the color filter array 522.

Thereafter, a second OCL 523 is formed on the color filter array 522with the thickness of about 5,000 Å in order to overcome a problem ofthe steps formed between boundaries of the color filters and to providea planarized surface where a third OCL will be formed. Afterward, athird OCL is formed with the thickness ranging from about 1,400 Å toabout 1,600 Å on the second OCL 523 and then, is patterned into apredetermined configuration by using a predetermined mask such as abinary mask, a PSM or the like, thereby forming openings 505 and apatterned third OCL 524. It is noted that the deposition thickness ofthe third OCL is determined by considering the depths of the openings505 for preventing the bridge phenomenon between adjacent microlenses.Herein, the openings 505 have widths of about 0.4 μm to about 0.6 μm. Inaddition, the widths of the openings 505 are smaller than those of thepatterned third OCL 524 in consideration of forming microlenses thereon,as shown in FIG. 5A.

After forming the openings 505, referring to FIG. 5B, a microlens layer528 is formed over the resultant structure with the thickness in therange of about 5,500 Å to about 7,500 Å including the patterned thirdOCL 524 and the openings 505. Herein, the microlens layer 528 employs amaterial such as silicon oxide-based photoresist with a high opticaltransmittance.

Thereafter, referring to FIG. 5C, the microlens layer 528 is patternedinto a predetermined configuration, thereby forming rectangularmicrolenses 528A on the patterned third OCL 524, wherein the width ofthe rectangular microlens 528A is relatively smaller than the width ofthe patterned third OCL 524 between the openings 505 in consideration ofa post flow process. In the fourth embodiment, since there is the secondOCL 523 beneath the third OCL, the color filter array 522 is not damagedduring the formation of the openings 505 because the patterning processfor forming the openings 505 is carried out till the top face of thesecond OCL 523 is exposed. Furthermore, it is possible to form eachopening 505 with a uniform depth.

Subsequently, referring to FIG. 5D, a flow process is carried out in astepper through a blank bleaching for converting the rectangularmicrolenses 528A to dome-typed microlenses 528B. During the blankbleaching, photo active compound (PAC) in the rectangular microlenses528A is dissolved by degrees, thereby decreasing coherent forcesthereamong gradually. Here, the blank beaching process is carried outfor about five minutes at about 150° C. In particular, a thermal processafter the flow process can promote the flow process more and more.

After carrying out the flow process, there are formed the dome-typedmicrolenses 528B as shown in FIG. 5E. During the flow process,overflowed substances 515 are collected in the openings 505 so that thebridge phenomenon between the adjacent microlenses is effectivelyprevented. Moreover, since the dome-typed microlenses 528B are formedwithin the area of the patterned third OCL 524, the dome-typemicrolenses 528B are uniformly formed not being lopsided to one side ofthe patterned third OCL 527.

Following the flow process, a curing process is carried out for about 5minutes at about 200° C., for hardening the dome-typed microlenses 528B.

Referring to FIG. 6, there is provided a schematic plane view settingforth an arrangement of each element in a unit pixel array of the CMOSimage sensor in accordance with the fourth preferred embodiment.

In FIG. 6, it is easily understood that each element, i.e., each layer,is well aligned in the unit pixel array not being lopsided to one sidethereof. In detail, the first OCL 521 has the same size to the secondOCL 523 because the first and the second OCLs 521, 523 are formed byusing the same mask (not shown), wherein the color filter array 522 isformed vertically between the first OCL 521 and the second OCL 523 asdescribed above. The color filter array 522 is disposed within the areaof the first and the second OCLs 521, 523. Furthermore, the patternedthird OCL 524 of an octagonal shape similar to the dome-typedmicrolenses 528B is formed within the area of a corresponding colorfilter. In addition, the dome-typed microlenses 528B are formed withinthe area of the patterned third OCL 524. Accordingly, the fourthpreferred embodiment provides an advantage that it is not difficult tomeasure the critical dimension (CD) of the dome-type microlenses 528Bbecause they are aligned only within the area of the patterned third OCL524.

As described above, in accordance with the preferred embodiments of thepresent invention, there are employed the openings in predeterminedlocations of the underlying OCL on which the microlenses will be formedso that it is possible to prevent the bridge phenomenon between theadjacent microlenses during the flow process, to thereby maximize thesize of the microlens and reduce a chip size. Accordingly, much morelights passing through the microlenses are concentrated in thephotodiode so that the CMOS image sensor has a good photosensitivity.

In addition, since the microlenses are formed within the area of thepatterned OCL, the microlens has the uniform width and height.Therefore, each focal length of the light passing through each microlensbecomes uniform, whereby increasing focused property to raise the imageintensity.

While the present invention has been described with respect to theparticular embodiments, it will be apparent to those skilled in the artthat various changes and modifications may be made without departingfrom the scope of the invention as defined in the following claims.

1. A method for manufacturing a CMOS image sensor having microlensestherein, the method comprising: preparing a semiconductor substrateincluding isolation regions and photodiodes obtained by a predeterminedprocess; forming an interlayer dielectric (ILD), metal interconnectionsand a passivation layer formed on the semiconductor substrate insequence; forming a first over-coating layer (OCL), a color filterarray, a second OCL and a third OCL on the passivation layersequentially; patterning the third OCL into a preset configuration,forming openings and a patterned third OCL; and forming dome-typedmicrolenses on the patterned third OCL, wherein the pattered third OCLhas an octagonal shape.
 2. The method as recited in claim 1, wherein thefirst OCL is formed with a thickness of about 6,500 Å.
 3. The method asrecited in claim 1, wherein the second OCL is formed with a thickness ofabout 5,000 Å.
 4. The method as recited in claim 1, wherein the thirdOCL is formed with a thickness in a range of about 1,400 Å to about1,600 Å.
 5. The method as recited in claim 1, wherein the forming of thedome-typed microlenses includes: forming a microlens layer on thepatterned third OCL; forming rectangular microlenses by patterning themicrolens layer into a predetermined configuration; and carrying out aflow process.
 6. The method as recited in claim 5, wherein the microlenslayer is formed with a thickness in a range of about 5,500 Å to about7,500 Å.
 7. The method as recited in claim 5, wherein the microlenslayer uses a silicon oxide-based photoresist material.
 8. The method asrecited in claim 1, wherein a width and a height of an opening isadjusted by controlling a dose amount.
 9. The method as recited in claim5, wherein the carrying out of the flow process includes: carrying out ablank bleaching process; carrying out a flow process at about 150° C.;and carrying out a curing process at about 200° C. in order to hardenthe dome-typed microlenses.
 10. The method as recited in claim 9,wherein the carrying out of the flow process at about 150° C. is carriedout for about 5 minutes at about 150° C.
 11. The method as recited inclaim 9, wherein the carrying out of the flow process at about 200° C.is carried out for about 5 minutes at about 200° C.